Vegter et al. in U.S. Pat. No. 3,536,734, Nelson in U.S. Pat. No. 4,390,680 and Nelson et al. in U.S. 4,394,497 disclose the preparation of resins from unsaturated hydrocarbons such as cyclopentadiene or oligomers thereof and a phenol or substituted phenol by reacting the unsaturated compound with the phenol in the presence of a Lewis acid catalyst and subsequently removing the excess phenol. When BF.sub.3 is employed as the catalyst, the phenol, when stripped from the product, contains corrosive fluorine-containing compounds which are detrimental to the piping and vessels in phenol recovery systems. It is therefore desirable to have available a method which would reduce or eliminate the amount of corrosive elements in the phenol recovered from the reaction mixture in the preparation of such phenol-hydrocarbon resins.